President Donald Trump recently invoked "manifest destiny" to outline a bold vision for America's space program. But what does this historic and controversial term mean when applied to outer space?

"Americans are explorers, builders, innovators, entrepreneurs and pioneers. The spirit of the frontier is written into our hearts," Trump says.

Trump says we're going to Mars. He may be making it harder to get there. President Donald Trump says we’re going to Mars, but don’t start packing your bags just yet. There are a lot of reasons to doubt that his plans will get us to the Red Planet, and he may even put us further behind schedule.

During his inaugural address, President Donald Trump said he wants 'American astronauts' on Mars. Where does a future Mars mission currently stand?

The United States will once again consider itself a growing nation, one that increases our wealth, expands our territory, builds our cities, raises our expectations and carries our flag

The president’s Inaugural Address linked landing on the Red Planet with Manifest Destiny, but left many of the specifics unclear.

During his second inauguration speech, President Donald Trump endorsed a Mars mission as a part of America’s push into new horizons.

President Trump vowed to send astronauts to Mars during his second inaugural address. "We will pursue our Manifest Destiny into the stars," he said, promising to send astronauts to plant the American flag on Mars. Elon Musk, the SpaceX CEO and Trump ally, was seated behind the president and gave a vigorous thumbs up at the remark.

The second Trump administration started with soaring rhetoric about sending humans to Mars but confusion about who was leading NASA on an acting basis.

NASA employees received a memo from acting agency administrator Janet Petro, Wednesday, mandating the closure of all diversity, equity, inclusion and accessibility initiatives and contracts.

But the language that startled me—maybe because I didn’t expect it, even from Donald Trump—was “manifest destiny.” Seriously.

In a daring vision for the future of space exploration, President Donald Trump, during his second inaugural address, declared that it is America’s